1. Field of Invention
The present invention relates to a seat back of an automotive seat, and more particularly to a a seat back of such construction that its foam cushion member is formed to have a pair of lateral protrudent bolster portions, one integral bag-like body of trim cover assembly having an opened lower end is affixed over the cushion member, and the upper surface side of the trim cover assembly is partly pulled and anchored into the cushion member.
2. Description of Prior Art
Referring to FIGS. 1 to 3, an ordinary seat back (SB) is comprised of a foam cushion member (4) with a seat back frame (5) embedded therein, and a trim cover assembly (3) of a bag-like type preformed into one integral body having one opened lower end.
The foam cushion member (4) is so formed as to have a pair of lateral protrudent bolster portions (41)(41), a flat central portion (42) and a recessed groove of generally inverted-U-shaped configuration which is defined in a lower part of the central portion (42). As shown, the recessed groove comprises a pair of vertical groove portions (45a)(45a) extending in and along the respective boundary lines between the lateral bolster portions (41)(41) and the central seating portion (42), and a horizontal groove portion (43) extending width-wise of and transversely of the cushion member (4).
Designation (44) denotes an insert wire which is embedded in the cushion member (4) such as to be disposed at the bottom of the foregoing horizontal groove portion (43).
The trim cover assembly (3) is formed in one integral body like a bag with one opening, so dimensioned to allow insertion of the above-described cushion member (4) thereinto, to thereby constitute such a seat back as shown in FIGS. 5 and 6, although not shown clearly in FIGS. 1 to 3. The trim cover assembly (3) has, defined therein, a pair of lateral bolster cover sections (3b)(3b), each being for covering the respective two lateral bolster portions (41) (41) of cushion member (4), a lower central cover section (3a) for covering the corresponding portion (42) of cushion member (4), and an upper central cover section (3a') for covering the upper central portion of cushion member (4), all of which are sewn together as shown.
In this sort of trim cover assembly, there are provided three anchoring members (2a), (2a) and (2b) to pull and anchor the frontal surface of the trim cover assembly into the cushion member (4) for firm securement thereupon. Each of those three anchoring members is formed from an elongated strip of cloth or the like, having a lower through-opening (2a-1) of a loop-like shape in section, as can be understood from FIG. 2.
Of the three achoring members, the two ones (2a)(2a) form a pair of height-wise anchoring members which are sewn to the left-side boundary between the corresponding left-side bolster portion (3b) and end of central cover section (3a), and the right-side boundary between the corresponding right-side bolster portion (3b) and end of central cover section (3a), respectively, as viewed from FIG. 1. Such two anchoring members (2a)(2a) are dependent from the reverse side of the trim cover assembly (3) and extend in the height-wise direction of the same (3). Another remaining one (2b) form a width-wise anchoring member which is sewn to the horizontal boundary between the upper end of upper central cover section (3a') and a lower end of lower one (3a), and extends in the width-wise direction of the trim cover assembly (3), dependent from the reverse side thereof. A width-wise securing wire (21) is inserted in the through-opening (2b- 1 ) of that width-wise anchoring member (2b).
FIG. 3 shows a conventional anchor securing strap (1') for use in each of the above-stated two height-wise anchoring members. (2a)(2a). The securing strap (1') is made of a rubber material on the whole, comprising a body portion (11'), one connecting end (11'a), another connecting end (11'b) and a a pull tab portion (11'c). Two hook-like latch elements (13)(14) of generally "C" shape are provided on both connecting ends (11'a)(11'b) of securing strap (1'), respectively. The anchor securing strap (1') is inserted in each of the two height-wise anchoring members (2a)(2a) and retained therein with the latch element (13) being connected to the end (21A) of the securing wire (21). With this state, the trim cover assembly (3) is affixed over the cushion member (4), with a care being paid to insure that the width-wise anchoring member (2b) and two height-wise anchoring member (2a)(2a) are respectively inserted into the horizontal groove portion (43) and two vertical groove portions (45a)(4a) and thereafter the width-wise anchoring member (2b). is connected to the insert wire (44) by means of hog rings (not shown), and the pull tab portion (11'c) is pulled along the longitudinal direction of the height-wise recessed groove (45a), as can be seen from FIGS. 2 and 6, although the FIG. 6 is not related to this prior-art structure, so that the connecting end (11'b) is secured to the horizontal frame (51) of the seat back frame (5) by engaging latchingly the latch element (14) over the female latch member (52) fixed on that horizontal frame (51). As a result, the two height-wise anchoring members (2a)(2a) are forcibly pulled down and expanded vertically in the respective two vertical recessed grooves (45a)(45a) along the longitudinal direction, by the elastic stretching force of the two securing straps (1')(1'). Thus, the frontal surface of trim cover assembly (3) is stretched over that of cushion member (4) to avoid slacked portion thereupon.
However, the employment of the rubber anchor securing straps (1')(1') has been found defective in that (i) the straps per se can not easily be inserted through the through openings (2a-1)(2a-1) of anchoring members (2a)(2a), respectively, due to their elasticity, which may require a guide wire or the like to facilitate the insertion of the straps. In comparison, the prior art rubber strap (1') results in an uneven pulling force on the anchoring member creating an undesirable creasing and wrinkling on the surface of the trim cover assembly over the seat back.